Medical Definition of Alcohol

Alcohol: An organic substance formed when a hydroxyl group is substituted for a hydrogen atom in a hydrocarbon. The type of alcohol used in alcoholic beverages, ethanol, derives from fermenting sugar with yeast. After alcohol is ingested, the body converts it to sugar-based fuel. Alcohol acts as a central nervous system depressant, and it may be part of solutions used as preservatives, antiseptics, or medications.